SPACE travel could cause Alzheimer’s with exposure to galactic cosmic radiation harming the brain, according to a new study.
The Earth’s magnetic field generally protects the planet and people in low earth orbit from such cosmic radiation, but once astronauts leave orbit they are exposed to constant showers of various radioactive particles.
“Galactic cosmic radiation poses a significant threat to future astronauts,” said Professor Kerry O’Banion from the University of Rochester Medical Centre (URMC) Department of Neurobiology and Anatomy and the senior author of the study.
“The possibility that radiation exposure in space may give rise to health problems such as cancer has long been recognised. But this study shows for the first time that exposure to radiation levels equivalent to a mission to Mars could produce cognitive problems and speed up changes in the brain that are associated with Alzheimer’s disease.”
With appropriate warning, astronauts can be shielded from dangerous radiation associated with solar flares. But other forms of cosmic radiation cannot be so effectively blocked.
Because this radiation exists in low levels, the longer an astronaut is in deep space, the greater the exposure – which could prove a worry for Nasa as the agency is planning manned missions to a distant asteroid in 2021 and to Mars in 2035. The round trip to the red planet could take as long as three years.
For more than 25 years, Nasa has been funding research to determine the potential health risks of space travel in an effort to both develop countermeasures and determine whether or not the risks warranted sending men and women on extended missions in deep space.
Several studies have demonstrated the potential cancer, cardiovascular, and musculoskeletal impact of galactic cosmic radiation, but, for the first time, this latest study, published in the journal PLOS ONE, examines the potential impact of space radiation on neurodegeneration, in particular the development of Alzheimer’s disease.
The researchers, who have been working with Nasa for eight years, studied the impact of a particular form of radiation called high-mass, high-charged (HZE) particles which are propelled through space at very high speeds by the force of exploding stars and come in many different forms.
For this study the researchers chose iron particles. Unlikely hydrogen protons, which are produced by solar flares, the mass of HZE particles like iron, combined with their speed, enable them to penetrate solid objects such as the wall and protective shielding of a spacecraft.
“Because iron particles pack a bigger wallop, it is extremely difficult from an engineering perspective to effectively shield against them,” said Prof O’Banion. “One would have to essentially wrap a spacecraft in a six-foot block of lead or concrete.”
A portion of the research was conducted at the Nasa Space Radiation Laboratory which has particle accelerators that, by colliding matter together at high speeds, can reproduce the radioactive particles found in space.
Tests on mice with models of Alzheimer’s showed that after they were exposed to various doses of radiation, including levels comparable to what astronauts would experience during a mission to Mars, they were far more likely to fail these tasks earlier than these symptoms would typically appear.
Prof O’Banion added: “This is yet another factor that Nasa, which is clearly concerned about health risks to its astronauts, will need to take into account as it plans future missions.”